Cost-effectiveness of Pertuzumab and Trastuzumab Biosimilar Combination Therapy As Initial Treatment for HER2-positive Metastatic Breast Cancer in Singapore

Background: This study evaluates the cost-effectiveness of pertuzumab with trastuzumab biosimilar and docetaxel as initial treatment for HER2-positive metastatic breast cancer (MBC) in Singapore.

Methods: A partitioned survival model with three health states was developed to evaluate the cost-effectiveness of trastuzumab biosimilar and docetaxel with or without pertuzumab from a healthcare system perspective over a 15-year time horizon for patients with HER2-positive MBC. Key clinical inputs were derived from the CLEOPATRA trial. Health state utilities were derived from the literature and direct medical costs were obtained from local public healthcare institutions.

Results: The base-case resulted in an incremental cost-effectiveness ratio (ICER) of SGD366,658 (USD272,244) per quality-adjusted life-year (QALY) gained. One-way sensitivity analyses showed that the ICER was sensitive to utilities in the progression-free state, price of pertuzumab and time horizon. When the price for trastuzumab reference biologic (branded) was applied, the ICER was even higher (SGD426,996 [USD317,045]/QALY).

Conclusion: Although trastuzumab biosimilar reduced the cost of the pertuzumab combination regimen, the ICER remained high and was not cost effective in Singapore's context. As pertuzumab contributed 80% of the overall combination treatment cost, price reductions for pertuzumab will be required to improve the cost-effectiveness of combination treatment to an acceptable level.